Measured CPAP power consumption

[archangle]

We often get questions about actual power consumption of CPAP machines.

For those of you with measurement capability, what do you get?

Here's one session data.

ResMed S9 AutoSet with heated humidifier. No heated hose.

Auto 18-20, EPR=3, humidifier=4. Fairly humid night. Room temp around 75F.

Kill a Watt power meter measuring AC power into the power brick.

4:32 hours.
0.15 Kilowatt (Correction Kilowatt hours)
Average power 34 watts.

Looking at the instantaneous power readings as I inhale and exhale and the heater runs, power varies all over the place. Between 15 and 90 watts read on the meter.

[avi123]

What is a "Kill a Watt power meter" ?

And what's the meaning of this:

4:32 hours.
0.15 Kilowatt
Average power 34 watts.


You don't measure Watts but Amperes and Voltage and calculate the Watts:

Looking at the instantaneous power readings as I inhale and exhale and the heater runs, power varies all over the place. Between 15 and 90 watts read on the meter.

[123.Shawn T.W.]

http://www.p3international.com/products ... 00-ce.html

Measures consumption

[napstress]

This is interesting, archangle. I unplug pretty much anything unpluggable when I'm done using them, with the exception of lamps, refrigerator, oven, in an effort to avoid phantom energy drain. I've often wondered to what degree I was canceling that out by using the CPAP all night long.

[avi123]

http://www.p3international.com/products ... 00-ce.html

Measures consumption

Thanks for showing the Kill a Watt.

[ozze_dollar]

I get a deduction from my power bill because I am a cpap user. It is about $19 a qtr. Dont know if it covers it or not.

[chunkyfrog]

We used the same device to determine our power cost for distilling water.
--About 13 cents a gallon in winter; 20 cents in summer.
(seasonal electric rates are different--especially with electric heat)


0

[avi123]

Here is a Typical Power Consumption of a household. What counts is Kilowatts Hours or Annual kWH:

http://www.oksolar.com/technical/consumption.html

If I take archangel's measurement numbers of:

4:32 hours.
0.15 Kilowatt = 150 Watts
Average power 34 watts

Then it means that the CPAP with the humidifier ON, is using 150 watts. If I multipy it by the 7 hours that I sleep nightly
and by 365 days in a year I get:

150 x 7 x 365 = 383,250 Watts = 383 kiloWatts Hours (KWH) per year.

So it consumes annually as a dishwasher which consume 363 KWH annually or twice as a window fan consuming 170 KWH annually.

If I assume that the average price of residential electricity was 12¢/kWh in the U.S. in December 2011, and ranged from 7.5¢ in Idaho to 36¢ in Hawaii, then the CPAP electrical consumption costs me:

383 KWH x 12 cents/KWH = 4,596 cents = app $46 annually.

[Lizistired]

Breathing all night.... Priceless!

[archangle]

4:32 hours.
0.15 Kilowatt = 150 Watts
Average power 34 watts

Sorry about that. It was 0.15 Kilowatt hours. Blame it on dain bramage.

For 4:32 hours, that's 34 watts average power usage.

Roughly 0.3 kWh for one night's use. 3-5 cents worth of electricity a night. $10 to 15 a year.

[archangle]

Further information:

My S9 AutoSet power supply draws about 2 watts when the machine is turned off.

My PRS1 Auto power supply appears to draw less than 1 watt when turned off.

[avi123]

Further information

The power supply (Brick) for the S9 comes in 90 watts and 30 watts capacities. I assume that the 90 watts is for use with the humidifier. On the S9 Autoset body it's written 24 volts DC and 3.75 amps (for system). If I multiply the two numbers I get 90 voltampers, which jibes with the 90 watts power supply.

So I am back to my first calculation and I don't need the Kill-a-Watts gadget.

The annual cost of electricity to run the S9 Autoset with the humidifier:

90 watts x 7 hours x 365 days = 229,950 watts hours= 230 KWH
230 KWH x 12 cents/KWH= 2,760 cents = $27.6 annually.
If I don't use the humidifier then its one third as much, about $9.5 annually.

[archangle]

Further information

The power supply (Brick) for the S9 comes in 90 watts and 30 watts capacities. I assume that the 90 watts is for use with the humidifier. On the S9 Autoset body it's written 24 volts DC and 3.75 amps (for system). If I multiply the two numbers I get 90 voltampers, which jibes with the 90 watts power supply.

So I am back to my first calculation and I don't need the Kill-a-Watts gadget.

The label rating on almost any electrical device will be a maximum number. Actual usage is almost always less.

This thread is about actual measured power consumption, not the ratings. In my case, it's about 1/3 of the rated maximum. If I were deciding what size battery I need for emergency back, I'd need a battery 3 times a large if I wanted to use the rated maximum.

If I want to figure out actual yearly cost, I need to use actual consumption, not rated maximum. You can use the rated maximum, but realize you're probably overestimating actual cost.

[Goofproof]

I get a deduction from my power bill because I am a cpap user. It is about $19 a qtr. Dont know if it covers it or not.

That means your niebhors are paying $15 extra a quarter, because your electric company allows you a discount that is out of line with your use, Socialism at it's best. Jim

[snoozysue]

Once again things seem to be much more expensive Down Under (Aust). Our electricty went up on 1st July due to the Carbon Tax. I received a letter from my supplier today with the new rates.
I have a "use of time" meter and now pay:
Peak Consumption (2pm - 10pm) - 53.59 cents
Shoulder Consumption (8am - 2pm) - 21.82 cents
Off Peak Consumption (10pm - 8am) - 13.42cents

Luckily when I sleep its Off Peak - not that would stop me sleeping now that I actually sleep!